Coring and crushing bit



April 17, 1951 CAMP 2,549,420

CURING AND CRUSHING BIT Filed March 25, 1948 fob r2 m. Camp Urzverztor figw- 2 Qbbokrzag Patented Apr. 17, 1951 CORING AND CRUSHING BIT John M. Camp, Tulsa, Okla., assignor to Standard Oil Development Company, a corporation of Delaware Application March 25, 1948, Serial Nb. 16,971

2 Claims. (01. 255-72) The present invention is directed to'improved drilling apparatus. In particular the invention relates to a type of coring and crushing bit for drilling hard formations in the earth,- whereby cutting elements cut a core of the formation and crushing elements pulverize this core. The invention is of particular application for use in drilling oil wells.

The art of drilling bore holes into the earth has been extensively developed. A wide variety of drilling bits, and "associated apparatus have been developed. However, one phase of boring operations in which much improvementis to be desired, is that encountered in boring through hard formations in the earth. When a hard formation is encountered, at the present time, it is generally necessary to employ especially constructed drilling tools, of expensive construction and short life. Frequently, the drilling rate attainable with even the best tools can be measured in inches per hour, rather than the desired feet per hour. A particular difficulty encountered in attempting to drill through a hard formation arises from the fact that While the circumference of a cutting tool may have a high enough rotational speed to cut adequately, the central part of the drilling tool does not have sufiicient speed. Consequently, while it is relatively simple to out a hard formation by circumscribing a core of the formation, it is relatively diflicult to cut the core itself. It is the principal object of this invention, therefore, to provide a drilling tool capable of readily breaking up this core.

While this invention has particular application to the actual drilling of oil wells, where depths of thousands of feet may be required, the drilling tool of the present invention also useful in drilling shot holes, in drilling holes for the application to thermal methods of seismic exploration, and in drilling holes'for sampling. In all these cases it may be that hard formations will be encountered whereby the necessity for using a special cutting tool as taught by the present invention may arise.

This invention may be understood more fully by referring to the accompanying drawing, wherein one embodiment of the cutting tool of this invention is shown. Referring to this drawing the numeral 5 refers to a drill hole being cut into the'earth through a hard formation 2. It is to be understood that conventional drilling tools may be used to cut the hole I until a hard formation is encountered. At that time the drilling tool of this invention may be employed to cut through the hard formation. 'As shown in the drawing the drilling tool is connected with, or may be an integral part of the drill string 3, which extends to the surface of the earth and is rotated by the conventional means. The inner part of this drill string comprising the cavity 4 is used to maintain a flow of mud through the drill string and on to the cutting and crushing surfaces of the drilling device to be described. Positioned at the lower extremity of the drilling device, are a group of cutting heads 5[ While two cutting heads are shown in'th e drawing, it is to be understood that'an'ynum ber may be employed. Approximately four such cutting heads are used conventionally. These cutting heads correspond to the conventional cutting heads employed in hard formation drillers. The angle at which they are set, and the manner in which their cutting surfaces are prepared are not part of the present inventio and so will not be described in detail. The action of these cutters depends upon the rotary action imparted by the drill string 3 which causes the cutters to roll along, biting and crushing the hard formation. A flow of drilling mud is maintained on the surface of these cutters from the .cavity 4 of the drill string 3, and through the chambers 6 terminating in an opening just above the cutters 5. Sulficient pressure is maintained on the drilling mud in the drill string so as to maintain a steady fiow of drilling mud through the chambers indicated, and on to, or adjacent to the cutting heads 5. It will be noted that rotation of the drill string 3 causes the cutters 5 to cut an annulus from the hard formation. As indicated, this is fairly readily achieved as the rotational rate of the drill string 3 may be maintained at a speed sufficient to secure good cutting action. A central core of the hard formation, indicated by the numeral 1 will be left by the cutting action of the cutters 5. It is this core which is difiicult to cut, or break up, when using conventional drilling tools. In accordance with the present invention, therefore, this core circumscribed by the cutters 5 is brought into contact with crushing reamers 8, positioned somewhat above the cutting heads 5. Again any number of reamers may be employed, and while two are shown in the drawing, it is generally preferred to employ more, for example 4. These reamers are mounted on a rotatable substantially vertical axis, permitting rotation of the reamers as the drill string 3 is turned. The rotation of the reamers thus causes their sharp cutting edges to cut into the core 1 left by the downward direction so that as the core I moves:

upwardly past the reamers 8 progressively smaller diameters of the core will be engaged by the reamers.

As described, the cutting tool. ofathis invention comprises a drilling tool employing conventional cutting elements. placed about the circumference of the lower extremity of the cutting tool so as to cut a;ring,.0r..

annulus from the hard formation in which the tool is used. This causes. a.-cylindricalcore .01 the hard formation to be cut, which core is then brought into contact witha pluralityof reamers adapted to cut, or crush the core; A flow of drilling mud is maintainedv on, oradjacent-to the :reamers and the cutting elements soas to aid the cutting and crushing action, and so as to wash away the particles formed. By employing the cutting tool of this invention, it is apparent that higher cutting rates will beobtainableethrough hard iormations;

Having now fully described. this invention, what is claimed; is:

1. A-drilhng tool for penetrating-hard forma- These cutting elementsaretions in the earth comprising a body attachable to a drill string, said body terminating in a lower hollow cylindrical portion, a plurality of primary cutting elements attached to the lower extremity of said body about the circumference thereof and adapted to cut an annulus of the formation and to leave a central core thereof, and a plurality of secondary crushing elements rotatably mounted on said body on'substantially vertical axes above said primary cutting elements, said crushing elements comprising elongate reamer members tapering inwardly toward their axes in a downward direction so that as said core-,,moveszupwardly past said members progressively small diameters of said core will be engaged by said members.

2.. Drilling ,tool. according to claim 1 including conduit means for fluid connecting the interior of said drill string with a region adjacent said primary cutting elements on the lower extremity of said. body and separate conduit means for fluid connecting the interior or" said drill string with a region adjacent said secondary crushing elements.

JOHN M. CAMP.

REFERENCES CITED The following references are of record in the fileof this patent:-

UNITED STATES PATENTS Number Name Date 1,322,696 Hughes Nov. 25,1919 2,022,101. Wright; .Nov. 26,1935 

